Among agronomic crops, fleshy roots and stems, such as tubers and bulbs, have become an important food source. Tubers, such as potatoes, carrots, beets, radishes and turnips, and bulbs, such as onions, should be eaten within a few months of harvest. Otherwise, sprouts may form, signaling a decrease in quality of the the crop. For example, the eyes of a potato are nodes where bud sprouts may grow leading to a decrease in starch content of the potato, making it less commercially desirable. In addition, once harvested, the tuber (or bulb) may lose weight through respiration and transpiration and may become blemished, dessicated and rotted.
Thus, an important consideration for distribution and sale of agronomic crops is the total time from harvest to ultimate consumer use. Unfortunately, crops are often stored for long periods of time prior to their ultimate use. Efforts have been made to minimize this time period and to extend the useful life of the crop such that it retains its utility and commercial appeal. Such efforts generally are directed to controlling ambient conditions such as ventilation, temperature, humidity, and light.
Chemicals have also been used to improve the storage life of agronomic crops. For example, tecnazene (Fusarex.RTM.), and CIPC or chloropham (Mirvale.RTM.) have been used for tuber sprout suppression. However, both of these products have problems.
Tecnazene, a fungicide, has been found to be toxic to fish downstream of processing plants. Residues have also been detected in soil and drinking water. In fact, a six week treatment withholding period has been set for making potatoes treated with tecnazene available for distribution. The unacceptably high toxicity and cost of tecnazene, and the increasing use of fungicides such as imazalil and TBZ to seed potatoes, have contributed to the decreasing use of tecnazene.
CIPC is an old and inexpensive product. The need to apply CIPC as a vapor, however, results in an uneven distribution when applied to crops in storage. Such uneven distribution leads to excessive, and potentially harmful residues. In addition, CIPC must be applied several times during the storage period leading to an increase in such residues. A three week treatment withholding period has been set for CIPC. Other chemicals, such as maleic hydrazide and various alkyl napththalenes, (e.g., DIPN) have also been used to inhibit sprout formation on such crops with little success.
Thus, there remains a need for an effective, low cost, environmentally friendly sprout suppressant.
It is therefore an object of this invention to provide a method of using herbicides to inhibit the growth of sprouts on tubers and bulbs.
It is further an object of this invention to provide a post-harvest sprout inhibiting treatment for tubers and bulbs which is easily and uniformly applied in a single treatment.
It is yet another object of this invention to provide a sprout inhibiting treatment which has low toxicity and a reduced treatment withholding period.
These and other objects of the invention will become apparent from the detailed description of the invention which follows.